Sort all valid elements according to a list of attribute values.

Parameter

  • attributes: The list of attribute names to use for sorting
  • ascending: Optional boolean values that flags, if the given list of attributes should be sorted in ascending or descending order. Default value is descending.

Note: Because of the non-decreasing order of time in a data stream sorting is only possible inside a relation with equal start and end timestamp.Output is only created after an element is read with a higher start time stamp than the highest end timestamp!


So in the following example, output is created after reading the last "a"-value.

a [0,10] --> no output

c [0,10] --> no output

b [0,10] --> no output

a [10,20] --> Output of three tuples a [0,10], b [0,10], c [0,10]

Example

PQL
Sort Operator
relation = ELEMENTWINDOW({SLIDE = 5, SIZE=5},  input)

/// Sort the stream by the attribute value id.
output = SORT({
                  attributes = ['id']
                 }, relation)

/// Sort the stream by the attribute id in ascending order.
output = SORT({
                 attributes = ['id'], 
                 ascending = ['true']
                }, relation)
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